The D&S has special summertime packages for hiking and rafting, but they certainly don't handle those activities themselves. For rafting, they partner with one of the local rafting companies here in Durango (Mild to Wild I think?) and only handle getting the rafting people, equipment, and passengers off or on the train. I recall bringing this up somewhere on the forum here how they could maybe partner with Silverton Avalanche School or some other company to host backcountry skiing excursions, and that the C&TS could do something like that as well. Would be interesting to see something like this could all handled under C&TS management but it'd certainly be a lot easier to do some sort of partnership with some sort of backcountry skiing tour guide association in the local area.
There are my two cents as a skier and an NG Nut myself...